Arrangement for grinding planar annular surfaces

ABSTRACT

The present invention relates to an arrangement for grinding planar annular surfaces (6; 8), especially the sealing surfaces of a valve. The arrangement comprises a hub (15) disposed rotationally fixed and bearing a planetary disc (16) mounted rotatably on the hub (15) and bearing in turn around its periphery a plurality of grinding heads (17) each having a grinding disc (19) mounted rotatably in its respective grinding head (17). The planetary disc (16) is effectively connected to a drive shaft (4) by means of which it can be caused to rotate relative to the hub (15). Between the hub (15) and the grinding discs (19) there are effective connections (31, 32, 33, 34, 35, 36) adapted to cause the grinding discs (19) to rotate relative to their respective ginding heads (17) when the planetary disc (16) is rotated relative to the hub (15). It is characteristic of the invention that the drive shaft (4) is mounted in the center of the hub ( 15) in such a way that it can be pivoted through approximately 180° in a plane normal to the planetary disc (16). This enables the grinding discs (19) to coincide with the planar annular surfaces automatically and irrespective of the inclination of the drive shaft (4) relative to the said planar annular surfaces.

The present invention relates to an arrangement for grinding planarannular surfaces, especially the sealing surfaces of a valve, comprisinga hub disposed rotationally fixed and bearing a planetary disc mountedrotatably on the hub and bearing in turn around its periphery aplurality of grinding heads each having a grinding disc mountedrotatably on its respective grinding head, this planetary disc beingeffectively connected to a drive shaft by means of which the planetarydisc can be caused to rotate relative to the hub, and wherein there areeffective connections between the hub and the grinding discs, adapted tocause the grinding discs to rotate relative to their respective grindingheads when the planetary disc is rotated relative to the hub.

Grinding arrangements of this type are used in particular for the finalgrinding of the sealing surfaces of valves. In the two main types ofvalve which exist, namely, shut-off valves and slide valves, the saidsurfaces are broadly speaking at right angles to the longitudinal extentof the valve spindle, or form a small angle with it. This has meant thatfor the final grinding of these two kinds of valve two different kindsof grinding arrangement have been required, which is naturally expensiveand impractical, particularly as the final grinding is usually carriedout on site by special assembly personnel.

A primary object of the present invention is to provide a grindingarrangement of the kind named in the introduction which is for generaluse, at least for the most usual kinds of valve, and this is madepossible due to the fact that the drive shaft is mounted in the centreof the hub in such a way that it can be pivoted through approximately180° in a plane normal to the planetary disc, thus enabling the grindingdiscs to coincide with the planar annular surfaces automatically andirrespective of the inclination of the drive shaft relative to the saidplanar annular surfaces.

The invention will be described in more detail in the following withreference to the accompanying drawing on which

FIGS. 1a and 1b show a grinding arrangement according to the inventionbeing used for the final grinding of sealing surfaces on a slide valveand on a shutoff valve, respectively.

FIG. 2 is a side view showing an embodiment of a grinding arrangementaccording to the invention during the grinding of the sliding componentof a valve.

FIG. 3 is a detail showing the construction of the grinding arrangementshown in FIG. 2, in perspective and at an angle from above.

FIG. 4 is a cross-section through the grinding arrangement.

In FIGS. 1 and 2 on the drawing, 1 is the designation of a grindingarrangement according to the invention which is mounted on a framework 2via a tubular element 3 in which the drive shaft 4 of the grindingarrangement is rotatably mounted. This shaft may be driven by means of ahand-drill tool 5, operated by electricity or compressed air, which canbe effectively connected to the outer end of the drive shaft 4. Via theframework 2 the grinding arrangement can be mounted on a valve housing 6for the final grinding of the valve seat 6, FIGS. 1a and 1b, or on acone cradle 7 for the final grinding of the cone or sliding component 8of the valve, FIG. 2. The purpose of the cone cradle 7 is to serve as asupport for the sliding component 8 of the valve and for the framework2. The latter comprises a mechanism 9 for centering and adjusting thedepth of the grinding arrangement, together with stop devices 10 and 11respectively for the centering and depth-adjustment. The setting of theappropriate grinding pressure is effected by means of a wheel 12 and aspindle 13 with a thread on it, and a pushing and pulling spring 14.

The grinding arrangement comprises a hub 15 which bears a planetary disc16 mounted so that it can rotate on the hub. Around its periphery thedisc has a plurality of grinding heads 17; in the embodiment shown onthe drawing the number of grinding heads is five. Each grinding head 17comprises a part 18 which is mounted so that it may slide radially inthe planetary disc 16, and a grinding disc 19 mounted rotatably on thispart. The planetary disc 16 is effectively connected to the drive shaft4 by means of which the planetary disc 16 can be caused to rotaterelative to the hub 15.

According to the invention the mounting of the drive shaft 4 ispositioned centrally on the hub 15 in such a way that the drive shaftcan be pivoted through approximately 180° in a plane normal to theplanetary disc 16. Furthermore, between the hub 15 and the grindingdiscs 19 there are effective connections adapted to cause the grindingdiscs 19 to rotate relative to their respective grinding head part 18when the planetary disc 16 is rotated relative to the hub 15.

The manner in which the planetary disc 16 is effectively connected tothe drive shaft 4, how the drive shaft 4 is mounted in the hub 15 andhow the latter is effectively connected to the grinding discs 19 willnow be described with reference in particular to FIGS. 3 and 4.

As can be seen in the said Figures, the hub 15 is equipped with twobrackets 20, 21 in which a transverse part 22 on the tubular element 3is mounted rotatably so that the said element 3 and with it the driveshaft 4 can be pivoted through approximately 180° in a plane normal tothe planetary disc 16. The effective connection between the drive shaft4 and the planetary disc 16, which is effective in every angularposition within the said angle of 180°, consists of two shafts 23, 24which are mounted rotatably in the transverse part 22, approximatelyparallel to the planetary disc 16. The ends of the shafts 23, 24 areequipped with conical gear wheels 25, 26, 27, 28, of which the opposinggear wheels 25, 26 engage with a conical gear wheel 29 on the driveshaft 4. The remaining gear wheels 27, 28 on the shafts 23, 24respectively engage with a conical gear ring 30 disposed concentricallyon the planetary disc 16. The rotation of the planetary disc 16 relativeto the hub 15 when the shaft 4 is rotated is achieved by means of thiseffective connection.

In order to achieve the rotation of the grinding discs when theplanetary disc 16 is rotated relative to the hub 15 an effectiveconnection is required between the latter and the respective grindingdiscs 19. For each of the respective grinding discs 19 this consists ofa spindle 31 mounted rotatably in the planetary disc and lying in aplane which is approximately parallel with that in which theintermediate shafts 23, 24 lie. The spindle 31 is equipped with twoconical gear wheels 32, 33, one 32 of which engages with a conical gearring 34 disposed concentrically on the hub 15. The other gear wheel 33engages with a conical gear wheel 35 disposed at one end of a shaft 36which is mounted rotatably in the part 18, and to the other end of whichthe grinding disc 19 is attached. The gear wheel 33 can be displacedalong the spindle 31 in order to allow valves of different sizes to beground.

By means of the above-described effective connections, when the driveshaft 4 is rotated the grinding discs 19 rotate around their shafts 36and, due to the rotation of the planetary disc 16 relative to the hub15, they also move in a circular path round the axis of rotation of theplanetary disc 16. Very smooth sealing surfaces are obtained in thisway. Moreover, the effective connection between the drive shaft 4 andthe planetary disc 16 is constructed in such a way that it allows thegrinding discs 19 to be angled relative to the drive shaft 4 within anangular range of approximately 180°.

I claim:
 1. An arrangement for grinding planar annular surfaces,especially the sealing surfaces of valves, comprising:a rotationallyfixed hub with a center; a rotatable planetary disc with a peripherymounted on said hub; a plurality of grinding heads generally mounted atsaid disc periphery; a grinding disc rotatably mounted on each of saidgrinding heads; a drive shaft with a conical gear mounted on said driveshaft; an intermediate shaft rotatably mounted on said hub and operablyconnected to said planetary disc; at least one intermediate shaft firstconical gear attached to said intermediate shaft; said drive shaftconical gear engaging said intermediate shaft first conical gear; saidintermediate shaft having a first shaft part and a second shaft partcentrally disposed on said planetary disc along a common center line,which center line is approximately parallel with said planetary disc,each of said first shaft part and second shaft part provided with asecond conical gear; a conical gear ring concentrically disposed on saidplanetary disc and engaging each of said second conical gears; saiddrive shaft operable to rotate said planetary disc; effectiveconnections connecting said hub and said grinding discs, which effectiveconnections rotate each of said grinding discs relative to theirrespective grinding heads when said planetary disc is rotated relativeto said hub; said drive shaft mounted at said hub center and pivotablethrough an angle of approximately 180° in a plane normal to saidplanetary disc, thereby enabling said grinding discs to automaticallyalign with said planar annular surfaces irrespective of the inclinationof said drive shaft relative to said planar annular surfaces.
 2. Anarrangement as claimed in claim 1 wherein said planetary disc defines aplane and, each of said effective connections between said hub and eachof said respective grinding discs includes a spindle with a spindlelongitudinal axis, which spindle is generally in a plane approximatelyparallel to said planetary disc plane, a spindle-contacting-conical gearring concentrically disposed on said hub, a spindle conical gear wheelattached to each of said spindles and engaging saidspindle-contacting-conical gear ring to rotate said spindles, a firstbeveled gear mounted on, rotatable with and axially movable along eachof said spindles, second beveled gears operably connected to each ofsaid grinding discs, each of said first beveled gears contacting andoperable to drive a second beveled gear and grinding disc, each of saidgrinding heads including a housing part; each of said first beveledgears and said second beveled gears operable with a grinding disc aremounted in a housing part, which grinding heads and housing parts aremounted in said hub, each of said housing parts with said first andsecond beveled gears and said connected grinding disc is non-rotationalabout said spindle and is axially and radially displaceable along saidspindle to align said grinding discs in said planetary disc.
 3. Anarrangement for grinding planar annular surfaces, especially the sealingsurfaces of valves, comprising:a rotationally fixed hub with a center; arotatable planetary disc with a periphery, which disc is mounted on saidhub; a plurality of grinding heads generally mounted at said discperiphery; a grinding disc rotatably mounted on each of said grindinghead; a drive shaft with a conical gear mounted on said drive shaft; anintermediate shaft rotatably mounted on said hub and operably connectedto said planetary disc; said intermediate shaft having a first shaftpart and a second shaft part centrally and coaxially disposed on saidplanetary disc along a common center line, which center line isapproximately parallel with said planetary disc, an intermediate shaftfirst conical gear and a second conical gear mounted and operable oneach of said first part and second shaft part; said drive shaft conicalgear engaging said intermediate shaft first conical gears; a conicalgear ring concentrically disposed on said planetary disc and engagingeach of said second conical gears; said drive shaft operable to rotatesaid planetary disc; effective connections connecting said hub and saidgrinding discs, which effective connections rotate each of said grindingdiscs relative to their respective grinding heads when said planetarydisc is rotated relative to said hub; said drive shaft mounted at saidhub center and pivotable through an angle of approximately 180° in aplane normal to said planetary disc, thereby enabling said grindingdiscs to automatically align with said planar annular surfacesirrespective of the inclination of said drive shaft relative to saidplanar annular surfaces.